refactor: reorganize skill numbering, remove obsolete skills, rename shared libs

- Rename: 00→80 claude-settings-optimizer, 88→79 dintel-skill-update,
  92→81 mac-optimizer, 93→82 tui-design-template
- Rename: dintel-shared → _dintel-shared (consistent with _ourdigital-shared)
- Remove: 61-gtm-manager, 62-gtm-guardian (obsolete), 99_archive
- Update all dintel-* skill refs (114 occurrences across 31 files)
- Sync README.md, CLAUDE.md, AGENTS.md with new structure

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

custom-skills/_dintel-shared/README.md

@@ -0,0 +1,32 @@
+# _dintel-shared — D.intelligence Agent Corps Shared Environment
+
+Shared Python package and utilities used by all `dintel-` Claude Skills (agents 70-77, 88).
+
+## Setup
+
+```bash
+cd /Users/ourdigital/Projects/our-claude-skills/custom-skills/_dintel-shared
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -e ".[dev]"
+```
+
+## Package Structure
+
+```
+src/dintel/
+├── __init__.py      # Version
+├── brand.py         # Brand constants, colors, service architecture, prohibited words
+├── document.py      # DOCX generation with D.intelligence branding
+├── excel.py         # Excel/xlsx generation with branded styles
+└── notion.py        # Notion database IDs, status options, client mappings
+```
+
+## Usage
+
+```python
+from dintel.brand import BRAND_NAME, SERVICE_MODULES, COLOR_PRIMARY
+from dintel.document import create_branded_doc, save_doc
+from dintel.excel import create_branded_workbook, style_header_row
+from dintel.notion import DB_TASKS_DASHBOARD, CLIENT_DB_MAP
+```